Series type vibration damper

ABSTRACT

A vibration damper for rotating members consisting of a hub member and at least two annular inertia members mounted upon the hub member by elastic elements. The hub and inertia members include cylindrical surfaces concentric to the axis of hub member rotation and the elastic elements cooperate with these surfaces for mounting one inertia member upon the hub member in a vibration absorbing relationship, and the second inertia member is mounted upon a cylindrical surface defined on the previously mentioned inertia member by an elastic element creating a &#39;&#39;&#39;&#39;series&#39;&#39;&#39;&#39; relationship between the inertia members and the hub member.

United States Patent Troyer 51 June 20, 1972 [541 SERIES TYPE VIBRATIONDAMPER Primary Examiner-William F. ODea [72] Inventor. William J.Troyer, Coldwater, Mich. Assistant Examiner F D. Shoemaker [73]Assignee: Simpson Industries Inc., Litchfield, Mich. Auomey-Beaman &Beaman 22 Filecli. July 13, 1970 [57] ABSTRACT [211 App 54,402 Avibration damper for rotating members consisting of a hub member and atleast two annular inertia members mounted U.S. CL 074/57, l B upon thehub mmber clasfic e]emenm The hub and inertia n l5/12 members includecylindrical surfaces concentric to the axis of [58] Field of Search74/574; 188/ l B hub member rotation and the dasfic elements cooperatewith these surfaces for mounting one inertia member upon the hub [56]Relmnm Cited member in a vibration absorbing relationship, and thesecond UNITED STATES PATENTS inertia member is mounted upon acylindrical surface defined on the previously mentioned inertia memberby an elastic ele- 2,585,382 2/1952 Guernsey..... ....74/574 m creatinga "series" relationship between the inertia 1 Paton nae-74,574 membersand he hub member 1,896,962 2/1933 Lee ....74/574 1,928,119 9/1933Vargha ..74/574 3 Claims, 4 Drawing Figures PATENTEfiJum 1912 3,670 593JNVENTOR WILLIAM J. TROYER FIG. 3 &

ATTORNEYS SERIES TYPE VIBRATION DAMPER BACKGROUND OF THE INVENTION Theinvention pertains to vibration dampers capable of absorbing anddissipating vibrations existing in rotary members such as crankshafts,drive shafts, propeller shafts and the like wherein an inertia member ismounted upon a hub element by vibratory movement and energy dissipatingmeans, such as an elastomer.

Vibration damping means are commonly employed with rotating members,such as crankshafts for internal combustion engines, drive shafts, drivetrains, and other rotary components. The purpose of such vibrationdamping means is to damp the torsional vibrations existing in a rotatingshaft, and as existing in the crankshaft of internal combustion enginessuch torsional vibrations are most troublesome, and will createdestructive forces unless controlled. The angular amplitudes ofvibration vary throughout the engine operating speed range andsignificant amplitudes occur at engine speeds that represent certainmultiples of the natural frequency of the mass elastic system. Torsionalamplitudes with their related vibration cycles per revolution occur atvarious speeds depending upon the characteristics of the engine masselastic system, or other rotating member. The mas elastic system of aconventional internal combustion engine which is not damped generallyhas only one mode of vibration which will be in a normal operating speedrange. This is said to be the first mode of vibration and this mode isthat excited by the harmonic torque variations of the engine and therewill be only one node in the crankshaft which is the location at whichthe angular movement of the shaft is zero.

The amount of vibrational energy added to an internal combustion enginecrankshaft is dependent upon the magnitude of the applied harmonictorque for a particular order of vibration and the phase angle at whichthis torque is applied. If the vibratory energy is large, the amplitudeis large and this amplitude would be infinite at resonant speeds if itwere not for the engines capacity for dissipating the vibratory energyin the form of friction heat. Thus, the amplitudes will rise until thebalance of energy addition equals the energy dissipation providing thatthe crankshaft does not break before this balance is attained. It can besaid that vibration damping is any means of absorbing the vibratoryenergy generated within an engine. A vibration damper should be locatedat the point of maximum amplitude in the mass elastic system and withmost internal combustion engine crankshafts this location is at thefront end of the crankshaft.

Various types of vibration dampers have been employed to absorbcrankshaft and rotating member vibrations, and the present invention isdirected to the type of damper which employs a hub member which may bedirectly connected to the crankshaft and having an inertia membermounted thereon by means of elastic vibratory movement and energydissipating means. in this type of vibration damper the elastic memberor rubber acts as a torsional spring which connects the damper inertiamember to the engine crankshaft. The inertia member and rubber orelastic element are so fabricated that the natural frequency of theassembly is a certain percentage of the natural frequency of the enginesmass elastic system. Tuning is accomplished by the proper selection ofthe physical dimensions of the elastic member, the proper shear modulusof the rubber compound and the proper amount of inertia in the inertiamember. With a tuned rubber damper the relative angle of twist betweenthe inertia member and the crankshaft may be three to four times theamplitude of the front of the crankshafi. This large relative motionmakes possible the conversion of large amounts of vibratory energy intoheat energy even though the amplitude of the front of the crankshafl issmall.

While most conventional vibration dampers utilizing hub and inertiamembers employ a single elastic vibratory movement and energydissipating member interposed therebetween they do not adequatelycontrol torsional vibrations throughout the engine speed range on somehigh specific output engines. Prior designs employing a plurality ofinertia members interconnected by elastic elements or viscous fluidsarranged in parallel are a matter of record. Reference is made to U.S.Pat. Nos. 2,594,555; 3,126,760; 3,207,000; and 3,285,096. With patentsof this type wherein aplurality of inertia members or components areutilized, separate vibratory movement and energy dissipating members maybe employed, one being employed with each inertia member, or the inertiamembers may be connected in parallel with respect to each other as inthe case with U.S. Pat. No. 3,285,096. However, this .type of multiplevibratory movement and energy dissipating arrangement, as used with aplurality of inertia members, is not completely efl'ective insuccessfully controlling certain types of vibrations, such as thoseoccurring at high internal combustion engine speeds, and the cost andcomplexity of this type of damper is excessive in view of themultiplicity of components involved, and in view of the complexmanufacturing and assembly techniques required.

SUMMARY OF THE INVENTION It is an object of the invention to provide avibration damper for rotary members wherein the damper consists of aseries arrangement of elastic vibratory movement and energy dissipatingmembers and masses which are capable of producing superior vibrationdamping characteristics, and permits an increased conversion of largeamounts of torsional vibratory energy into heat energy.

In the practice of the invention a hub member is employed which isattached to the rotating member in which the vibrations exist which areto be damped. The hub member includes a surface concentric with itsrotational axis upon which is mounted an elastic vibratory movement andenergy dissipation element, which inturn affixes an annular inertiamember to the hub member. The clearance between the hub and inertiamembers is such that the elastic element is under a predetermined stateof compression whereby a known tuned relationship exists between thedamper components. Of course, the amount of inertia of the inertiamember is known to introduce known factors into the vibration absorbingcharacteristics of the damper. The damper of the invention departs fromthe aforedescribed conventional configuration in that the inertia memberhas an annular concentric surface portion defined thereon which alsocooperates with an elastic vibratory movement and energy dissipationelement which in turn is employed to mount another inertia member to theassembly. The second inertia member is thereby affixed to the firstinertia member by a compressed elastic element, and the first inertiamember constitutes the sole mechanical support for the second inertiamember. Thus, a series relationship between the two inertia members isproduced.

A rotary vibration damper having a single elastic vibratory movement andenergy dissipation element and a single inertia member will produce anarrangement wherein the inertia member can have two to four times theangular movement of the hub. in the arrangement of the invention thefirst inertia member can have two to four dates the angular movement ofthe hub, and the second inertia member can have two to four times theangular movement of the first inertia member. Thus, since the frictionwork that can be done by a damper is a function of the friction index ofthe elastic member, such as rubber, the spring constant, andthe squareof the relative arnplitude between the damper parts, it is possible toconvert large amounts of torsional vibratory energy into heat energywith the construction of the invention. While the disclosed embodimentof the damper illustrates arrangements utilizing only two inertiamembers mounted upon a single hub, it would be possible to interconnectthree, or more inertia members in a series relationship if the vibratorycharacteristics of such a damper were required.

As the manufacturing techniques, and the assembly procedures involved inthe manufacture and assembly of vibration dampers in accord with theinventive concept are similar to those employed in the construction ofmore conventional single elastic element dampers, the invention can beeconomically practiced without requiring expensive or new assemblyapparatus and techniques.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects andadvantages of the invention will be appreciated from the followingdescription and accompanying drawings wherein:

FIG. 1 is an elevational, sectional view of a vibration damperconstructed in accord with the invention as taken along Section II ofFIG. 2,

FIG. 2 is a side elevational view of the damper of FIG. 1,

FIG. 3 is a view similar to FIG. 1 of another embodiment of vibrationdamper in accord with the invention, and

FIG. 4 is a graph indicating the improvement achieved by the utilizationof a series type damper in accord with the invention as compared with aconventional damper with respect to the sixth order of vibrationamplitudes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Rotary vibration dampers of thegeneral tuned type disclosed wherein an elastic vibratory movement andenergy dissipation element is employed to assemble a hub and annularinertia member vary in form depending upon the particular application.The embodiment shown in FIG. 1 is a simplified embodiment whichillustrates the basic concepts of the invention.

In the drawings, the hub member is represented at and consists of agenerally cylindrical element having a central opening 12 and aplurality of holes 14 defined in the web of the hub for receiving themounting bolts whereby the hub may be firmly affixed to the front end ofan internal combustion engine crankshaft, or other rotating element inwhich the vibrations to be damped occur. The hub includes an axiallyextending, outer, cylindrical, circumferential surface 16 as will beappreciated from FIG. 1. v

The first or inner" annular inertia member 18 is of a cylindricalconfiguration having an axial length corresponding to that of the hubmember 10 and includes an inner cylindrical surface 20, of a diametergreater than that of the hub surface 16. Also, the inertia memberincludes an outer circumferential cylindrical surface 22. An elasticvibratory movement and energy dissipation element 24 is interposedbetween the hub surface 16 and the inertia member. surface 20, and thismember may be formed of a rubber or similar material. Preferably, theelastic element 24 is inserted between the surfaces 16 and 20 undercompression in that the radial dimension of the gap or clearance betweenthe surfaces is less than the normal radial thickness of the element.Thus, as the element 24 is confined between the surfaces 16 and 20, itsresilient tendency to expand produces a high frictional engagement withthe engaged surfaces to form a finn assembly of the hub and inertiamembers. The aforedescribed relationships between these components isbasically similar to that described in the assignees U. S. Pat. No.3,088,332.

The second inertia member 26 is also of an annular configurationincluding an outer cylindrical surface 28, and an inner cylindricalsurface 30 of a diameter greater than the diameter 22 of the inertiamember 18. As will be appreciated from FIG. 1, the inertia member 26 isassembled to the inertia member 18 by means of an elastic element 32which has a normal radial thickness greater than the radial dimension ofthe spacing between the surfaces 22 and 30 whereby the element will beunder compression and thereby maintain a firm assembly of the inertiamember 26 upon the inertia member 18.

It will be noted that the axial length of the elastic element 32 isillustrated as being less than the axial dimension of the inertia member26 and the hub member 10, and tuning can be achieved by varying theaxial length of the elastic element, as well as the hardness and othercharacteristics of the element.

Holes 34 are illustrated as being formed in the inertia member 18 forbalancing purposes.

From the aforedescribed instruction it will be appreciated that theinertia members 18 and 26 are mounted in series" with each other in thatthe inertia member 18 constitutes the sole mechanical support for theinertia member 26 with respect to the hub member 10.

Where a conventional damper, which would consist of the hub member 10,the inertia member 18 and the elastic element 24 adds a second mode ofvibration, a two-noded vibration, within the normal operation of aninternal combustion engine, the disclosed embodiment utilizing anadditional inertia member connected in series with the inertia member 18adds a third, a three-noded, vibration within the normal operation ofthe engine. The inertia member 18 can have two to four times the angularmovement of the damper hub 10, and the inertia element 26 can have twoto four times the angular movement of the inertia member 18. As thefriction work done by the damper is a function of the friction index ofthe rubber, the spring constant and the square of the relative amplitudebetween the damper parts, the arrangement of the invention permitsconsiderably larger amounts of torsional vibratory energy to bedissipated than previously known constructions. It has been found thatthis type of series damper is particularly effective with high speedengines at the upper ranges of the engine velocity wherein vibrationsbeyond that capable of being efi'ectively damped by conventional dampersmay be controlled.

In the embodiment of FIG. 3 the hub member is represented at 36, and isadapted to be mounted upon the rotating member in which the vibrationexists, such as in a crankshaft, or the like. The hub 36 includes anouter circumferential, axially extending cylindrical surface 38.Thefirst or inner" inertia member 40 is of an annular configurationincluding an inner cylindrical surface portion 42 of a diameter greaterthan the hub surface 38 whereby the elastic vibratory movement andenergy dissipating element 44 may be inserted therein in a compressedstate, as previously described. In this manner the inertia member 40 isfirmly mounted upon the hub member 36. As is often employed, V-beltgrooves may be defined in the outer circumference of the inertia member.

The axial length of the inertia member 40 is greater than that of theaxial length of the hub 36 whereby the surface 42, if

extended, defines a cylindrical surface portion 46. A second annularinertia member 48 is in alignment with the surface portion 46 andincludes an outer circumferential cylindrical surface 50 of a diameterless than the diameter of the inertia member surface 46 and an elasticelement 52 is interposed therebetween as will be appreciated. Thus, inthis manner the inertia member 48 is mounted upon the inertia member 40,in a series relationship, and the aforedescribed advantages of this typeof relationship between a plurality of inertia members will be present.

In the embodiment of FIG. .3 the overall diameter of the vibrationdamper may be reduced as compared to the arrangement of FIG. 1, althoughthe axial length may be increased. While the disclosed embodimentsillustrate two inertia members interconnected in series on a commonhub,'it will be appreciated that three or more inertia members could beconnected in series to add even further capacity to the damper, shouldthe requirement exist. Both the inertia member 26 and the inertia member48 include annular cylindrical surfaces to which an elastic element maybe associated to cooperate with a third inertia member in a manner whichwill be apparent to one skilled in the art. I

The graph in FIG. 4 indicates a comparison of the vibratory dampingcharacteristics of a damper constructed in accord with the invention, ascompared with a damper utilizing a single inertia member. In the graphthe vertical indicia indicates double amplitude in degrees, while thehorizontal relationship indicates the speed of rotation of the memberbeing damped and in this case, the crankshaft of a high specific outputdiesel truck engine in speeds of hundrech of RPMS. The dotted linerepresents the angular deflection in degrees of the damped hub of theconventional rubber vibration damper, and it will be appreciated thatbetween 2,800 and 3,000 RPM the vibration becomes very high. The fullline on the graph of FIG. 4 represents the vibration dampingcharacteristics of a vibration damper constructed in accord with theinvention and it will be appreciated that in the 2,800 to 3,000 rangethat the vibration has been significantly reduced. Both of theillustrated curves indicate sixth order vibration amplitudes related tothe vibration cycles per revolution of the engine crankshaft.

It is appreciated that modifications to the inventive concept may beapparent to those skilled in the art without departing from the spiritand scope of the invention.

I claim 1. A torsional vibration damper for a rotary member comprising,in combination, a hub member adapted to be mounted upon the rotarymember for concentric rotation therewith, said hub member including anaxially extending first cylinder surface concentric to the axis ofrotation of the rotary member, a first annular vibratory movement energyabsorbing and dissipating elastic element mounted upon said hub memberfirst surface, a first inertia member mounted upon said first energyabsorbing and dissipating elastic element, said first inertia memberhaving first and second axially extending cylindrical surface portionsconcentric to each other and concentric to said first cylindricalsurface, said first elastic element being interposed between said firstsurface and said first surface portion supporting said first inertiamember 'upon said hub member, a second annular vibratory movement energyabsorbing and dissipating elastic element mounted on said first inertiamember second cylindrical surface portion, a second inertia membermounted upon said second energy absorbing and dissipating elasticelement, said second inertia member having a third axially extendingcylindrical surface portion concentric to said second surface portion,and said second elastic element being interposed between said second andthird surface portions supporting said second inertia member upon saidfirst inertia member whereby said second inertia member is mounted uponsaid hub member in a series relationship through said first and secondenergy absorbing and dissipating elastic elements and said first inertiamember.

2. A torsional vibration damper for a rotary member comprising, incombination, a hub member adapted to be mounted upon the rotary memberfor concentric rotation therewith, said hub member including an axiallyextending outer circumferential cylindrical surface concentric to theaxis of rotation of the rotary member, a first vibratory movement energyabsorbing and dissipating elastic element mounted upon said hub member,a first inertia member mounted upon said first energy absorbing anddissipating elastic element having an inner cylindrical surface portionand a second cylindrical surface portion concentric to said innersurface portion constituting an axial extension of said innercylindrical portion, a second vibratory movement energy absorbing anddissipating elastic element mounted upon said first inertia member, asecond inertia member mounted upon said second energy absorbing anddissipating elastic element having a second cylindrical surface, saidfirst elastic element being interposed between said outer surface andsaid inner surface portion, and said second elastic element beinginterposed between said second surface portion and said secondcylindrical surface whereby said second inertia member is radiallydisposed inwardly of said first inertia member and said second inertiamember is mounted upon said hub member in a series relationship throughsaid first and second energy absorbing and dissipating elastic elementsand said first inertia member.

3. A torsional vibration damper for a rotary member comprising, incombination, a hub member adapted to be mounted upon the rotary memberfor concentric rotation therewith, said hub member including an axiallyextending outer circumferential cylindrical surface concentric to theaxis of rotation of the rotary member, a first vibratory movement energyabsorbing and dissipating elastic element mounted upon said hub member afirst inertia member mounted upon said first energy absorbing anddissipating elastic element, said first inertia member including aninner cylindrical surface portion and a second cylindrical surfaceportion concentric to said inner surface portion radially outwardlydisposed of said inner surface portion constituting the outercircumference of said first inertia member, a second vibratory movementenergy absorbing and dissipating elastic element mounted upon said firstinertia member, a second inertia member mounted upon said second energyabsorbing and dissipating elastic element, said second inertia memberincluding a second cylindrical surface constituting an inner surface ofsaid second inertia member, said first elastic element being interposedbetween said outer surface and said inner surface portion, and saidsecond elastic element being interposed between said second surface faceportion and said second cylindrical surface whereby said second inertiamember is mounted upon said hub member in a series relationship throughsaid first and second energy absorbing and dissipating elastic elementsand said first inertia member.

1. A torsional vibration damper for a rotary member comprising, incombination, a hub member adapted to be mounted upon the rotary memberfor concentric rotation therewith, said hub member including an axiallyextending first cylinder surface concentric to the axis of rotation ofthe rotary member, a first annular vibratory movement energy absorbingand dissipating elastic element mounted upon said hub member firstsurface, a first inertia member mounted upon said first energy absorbingand dissipating elastic element, said first inertia member having firstand second axially extending cylindrical surface portions concentric toeach other and concentric to said first cylindrical surface, said firstelastic element being interposed between said first surface and saidfirst surface portion supporting said first inertia member upon said hubmember, a second annular vibratory movement energy absorbing anddissipating elastic element mounted on said first inertia member secondcylindrical surface portion, a second inertia member mounted upon saidsecond energy absorbing and dissipating elastic element, said secondinertia member having a third axially extending cylindrical surfaceportion concentric to said second surface portion, and said secondelastic element being interposed between said second and third surfaceportions supporting said second inertia member upon said first inertiamember whereby said second inertia member is mounted upon said hubmember in a series relationship through said first and second energyabsorbing and dissipating elastic elements and said first inertiamemBer.
 2. A torsional vibration damper for a rotary member comprising,in combination, a hub member adapted to be mounted upon the rotarymember for concentric rotation therewith, said hub member including anaxially extending outer circumferential cylindrical surface concentricto the axis of rotation of the rotary member, a first vibratory movementenergy absorbing and dissipating elastic element mounted upon said hubmember, a first inertia member mounted upon said first energy absorbingand dissipating elastic element having an inner cylindrical surfaceportion and a second cylindrical surface portion concentric to saidinner surface portion constituting an axial extension of said innercylindrical portion, a second vibratory movement energy absorbing anddissipating elastic element mounted upon said first inertia member, asecond inertia member mounted upon said second energy absorbing anddissipating elastic element having a second cylindrical surface, saidfirst elastic element being interposed between said outer surface andsaid inner surface portion, and said second elastic element beinginterposed between said second surface portion and said secondcylindrical surface whereby said second inertia member is radiallydisposed inwardly of said first inertia member and said second inertiamember is mounted upon said hub member in a series relationship throughsaid first and second energy absorbing and dissipating elastic elementsand said first inertia member.
 3. A torsional vibration damper for arotary member comprising, in combination, a hub member adapted to bemounted upon the rotary member for concentric rotation therewith, saidhub member including an axially extending outer circumferentialcylindrical surface concentric to the axis of rotation of the rotarymember, a first vibratory movement energy absorbing and dissipatingelastic element mounted upon said hub member, a first inertia membermounted upon said first energy absorbing and dissipating elasticelement, said first inertia member including an inner cylindricalsurface portion and a second cylindrical surface portion concentric tosaid inner surface portion radially outwardly disposed of said innersurface portion constituting the outer circumference of said firstinertia member, a second vibratory movement energy absorbing anddissipating elastic element mounted upon said first inertia member, asecond inertia member mounted upon said second energy absorbing anddissipating elastic element, said second inertia member including asecond cylindrical surface constituting an inner surface of said secondinertia member, said first elastic element being interposed between saidouter surface and said inner surface portion, and said second elasticelement being interposed between said second surface face portion andsaid second cylindrical surface whereby said second inertia member ismounted upon said hub member in a series relationship through said firstand second energy absorbing and dissipating elastic elements and saidfirst inertia member.